The NBA will use this July’s Las Vegas Summer League to test out a new coach’s challenge system for referees’ calls, sources tell ESPN’s Brian Windhorst. According to Windhorst, league officials are still working out the exact details of how the system will work, but it won’t involve a flag like the NFL.

As Windhorst observes, the NBA has frequently used the Summer League as a testing ground for possible changes to the game, including expanding officiating crews and adjusting goaltending rules.

Despite the fact that the league has increased its use of replay in recent years, a coach’s challenge system is unlikely to take effect in the NBA next season either, even if the Summer League experiment goes well.

The NFL, NHL, and MLB all currently employ some form of coach’s challenges, but each league has a number of rules governing which calls can and can’t be contested.